1. Field of the Invention
This invention relates to recording instruments, and more particularly to devices and methods for applying characters to a surface.
2. Description of the Prior Art
Due to the innovations of modern technology, it is now possible and practical to store alpha-numeric data in a variety of ways other than the standard approach using printed memoranda on a paper recording medium. Examples of such storage techniques include magnetic tape recorders, computer disc files, and semiconductor memories in computers and calculators. In order to use data stored in these ways, it is often necessary to have a way to reduce the data to humanly readable form. Methods for accomplishing this important task include the use of television screens (as are often used in airports for plane schedule monitors), teletypewriters, ticker tape machines, "X-Y" plotters, and also movable printers that apply the data characters to a writing surface as the printer is drawn across the surface. Two types of such movable printers known in the prior art are the matrix print head rolling printer and the ink jet moving printer.
One matrix print head rolling printer is described "Selectable Area Television Printer/Plotter" by S. Kambic, IBM Technical Disclosure Bulletin, Vol. 17, No. 2, July 1974, pages 565-567. That printer uses a printing mechanism in which many marking tips are arranged in a rectangular array. These tips are separately controlled in their vertical movement with respect to the printing surface so as to approximate any alpha-numeric symbols when they strike the surface in a variety of patterns as the printer is rolled across the surface. Although this matrix approach is suitable for its purpose, it is relatively complex and expensive.
An ink jet moving printer is shown in U.S. Pat. No. 3,656,169 to T. Kashio and has an ink depositing mechanism which controls an electrostatically charged stream of ink with deflection electrodes in a manner similar to the technique for controlling an electron beam in a cathode ray tube. Responsive to the changing voltage levels on the control electrodes, the stream of ink traces out characters on a printing surface as the printer is being moved across the surface. The ink stream control mechanism of this type of printer is useful for some applications, but it is a costly precision device requiring fine alignment and adjustment.
Objects of the present invention include simplifying movable printers and rendering them more reliable and less costly movable printers than those of the prior art.